Unabsorbed depreciation set-off rules govern priority, indefinite carry forward, and limited exceptions for reorganisations. Set-off and carry forward of unabsorbed depreciation follows a priority order in which current year depreciation is adjusted first, then brought forward business losses, and lastly unabsorbed depreciation. Any balance not absorbed is carried forward, generally indefinitely, and may be set off against income under any head other than salary. The same assessee rule applies in ordinary cases, though specified succession, amalgamation, demerger, and related reorganisation provisions create exceptions.